1. Field of the Invention
The present invention relates to a CAD program, a structure design system, and a structure design method, which are useful in particular for efficiently designing a structure composed of a plurality of frame members.
2. Description of the Related Art
Conventionally, in machine working plants, there has been used a base for installing a manufacturing machine or the like, and an apparatus cover for protecting such a machine or the like. In semiconductor plants or like plants, a clean booth has been used so as to install a semiconductor manufacturing apparatus or the like in a clean environment. These structures such as a base are constructed by attaching doors, wall panels, etc. to a basic frame, which serves as the skeleton of the structure. The basic frame is constructed by connecting a plurality of elongated frame members made of, for example, aluminum.
A manufacturer of such a structure designs a structure as a ready-made product for general applications. Further, the manufacturer designs a structure to be used by an ordering party on the basis of specifications of the structure, and delivers members which constitute the structure to the ordering party, along with drawings used for assembling the members. Further, in a case where the number of the members is large, a great burden is imposed on a worker if the steps of assembly are not clearly shown. Therefore, not only a drawing showing the entire configuration of the structure but also drawings (so-called sub-assembly drawings) for main portions of the structure are output and supplied to the ordering party.
In general, a CAD system is used for designing such a structure. For example, design of structures is performed by making use of a three-dimensional CAD system (see, for example, Japanese Patent Application Laid-Open (kokai) No. 2003-36279. In this case, the shapes of various members are defined by three-dimensional data, these members are assembled on the CAD system so as to complete a structure, and drawings of the structure as viewed from six directions or like drawings are output. In the case where design is performed by making use of a three-dimensional CAD system, an operator can readily grasp the shape or the like of a structure by viewing the structure from various angles. In addition, a perspective drawing or a like drawing which is useful for assembly of the structure can be readily output. Meanwhile, design of structures is also performed by making use of a two-dimensional CAD system, and two-dimensional data can be readily produced by placing the structure represented by three-dimensional data, while changing the viewing angle. Design by use of a two-dimensional CAD system is advantageous in that an operator is not required to have a high degree of skill, and design can be completed with a shorter period of time, as compared with the case where a three-dimensional CAD system is used.
However, the conventional designing by use of a three-dimensional CAD system requires an operator to have a high degree of skill, and even an operator having a high degree of skill takes a longer time for design, as compared the case where the operator uses a two-dimensional CAD system. In the case of designing by use of a two-dimensional CAD system, design errors easily occur, because grasping of the shapes of members or the like is difficult, as compared with the case where a three-dimensional CAD system is employed.
Further, since an actual structure is constructed in accordance with drawings output from a three-dimensional CAD system, the operator must design the structure by use of the three-dimensional CAD system, while checking whether or not the structure can be assembled in actuality. Further, in order to output sub-assembly drawings, the operator must consider the assembly sequence of the structure. That is, the operator is required to have a certain degree of experience and engineering knowledge regarding assembly of the structure, and merely knowing the operation of the three-dimensional CAD system well is insufficient.
As described above, designing a structure by use of a three-dimensional CAD system has a problem in that an operator is required to have a high degree of skill, and a long time is needed to complete the design.